Valve-gear for compound engines



(No Model.)

W. BPEARSON.

2 Sheets-Sheet l.

VALVE GEAR EUR GOMPOUND ENGINES.

. A WWA/55555 Mgr-0W 1288811888 Deo. 25, 1888.v

2 Sheets-Sheet 2.

(No Model.)

W. E. PEARSON. VALVE GEAR EOE GOMEOUND ENGINES.

No. 394,993. Patented Dec. 25, 1888.

/N VEN TUR;

N PETERS. Phuwumogmpm. wnsningm y UNITED STATES PATENT OEEICE.

IVILLIAM E. PEARSON, OF SAUGUS, ASSIGNOR TO NATHAN H. DANIELS, OF

BOSTON, MASSACHUSETTS.

VALVE-GEAR FOR COMPOUND ENGINES.

SPECIFICATION forming part of Letters Patent No. 394,993, dated December25, 1888.

Application filed November 26, 1887. Serial No. 256,215. (No model.) Y

To all whom t may concern; steam by using two or more cylinders in con-Be it known that I, VILLIAM E. PEARsoN, nection, and exhausting thesteam from the of Saugus, in the county of Essex and State Iirst or maincylinder into the second, and so of Massachusetts, have invented certainnew on. In the present instance two cylinders are 5 5 5 and usefulImprovements in Valve-Gear for shown arranged inv tandem fashion and iCompound Engines, of which the following is adapted to be worked so asto rotate the crank a specification. in both directions, forward andback. It is My invention relates to steam-engines, and also well knownthat an engine adapted to more particularly to the valve-gear of the runboth ways is provided with two eccen- 6o. 1o same, and has for itsobject to provide a simtrics-one for the advancing motion, and plemechanism to operate the valve of the known as the forward eccentric,and one second cylinder of the class of steam-engines for the backingmotion, and called the backknown as compound engines. ing eccentric.These eccentricsare connected My invention consists in the combination,to a Iink, so called, the forward eccentric 65 15 with the usualvalve-gear of a reciprocating at the top and the backing eccentric atthe engine, of an additional eccentric having a bottom of the same.Motion is communicated limited play on the crank-shaft of the engine, tothe valve by means of a rod connected to a connection between saideccentric and the the same and leading to the link-block, which valve ofthe second cylinder, and means is movable in the link to vary the lengthof 7o' 2o whereby said eccentric is converted by the stroke of thevalve.

rotation of the crank-shaft either into a for- Heretofore it has beenthe custom to use a ward or backing eccentric, and thus caused to secondset of eccentrics and links to operate operate the valve of the secondcylinder in the valve of the second cylinder. These deunison with thatof themain cylinder whether vices render the construction and operation75 2 5 the crank-shaft is rotated forward or backof engines of thisclass complicated and eX- ward, as I will now proceed to describe.pensive and occupy considerable space, so

Of the accompanying drawings, forming a that their'arrangement isoftentimes a diffipart of this specification, Figure I represents cultmatter. a side elevation of a (tandem) compound By my improvements I doaway with the 8o 3o engine embodying my improvements7 the necessity ofduplicating eccentrics and links shaft of the same being shown insection. for operating the valve of the auxiliary or Fig. 2 represents atop plan view and partial second engine, and substitute for the secondsection on the line fr, Fig. l. Fig. 3 represents set heretoforeemployed more simple and coma section on the line al Fig. l. 4 and 5pact operating devices, all of which I will now 8 5 3 5 represent detailviews, hereinafter referred proceed to describe.

to. Fig. G represents a diagrammatic view of Of the drawings, a arepresent steam-cylthe valve-gear of a link-motion engine in inders ofcommon construction, secured in full gear forward and the relationthereto any suitable manner so that they shall be in of my improvements,showing the cylinders line, as shown in Figs. 1 and 2. 9o 4o with thesteam-chests removed. Fig. 7 repreb represents the pisto n-rod, arrangedin sents a section on line 1/ y, Fig. 6, showing such manner as to passthrough cylinder a the position of valves, eccentrics, and pistons andinto cylinder d', and constituting a single in Fig. 6. Fig. S representsa view of the piston-rod for the two cylinders, the pistons valve-gearrepresented in Fig. 6, as it appears b b2 being secured to said rod inany suitable 95 45 in full gear back, showing the position of themanner. In the present instance I have at eccentrics, valves, andpistons as opposite to tached the steam-chests c c to the sides of thatshown in Figs. 6 and 7. Fig. 9 reprethe cylinders a a', as the mostconvenient arsents also a detail view, which will be fully rangement.explained hereinafter. CZ represents the valve-rod which connects roo 5oIt is well known that compound engines the main valve g of cylinder a'tothe linkare intended for the more economical use of block d. Said rod ispivotally connected to said block, which is moved forward and back bythe eccentrics e c through the eccentricrods f j" and link f2, the valveg being thus operated in the usual manner-that is to say, when the linkis adjusted by the usual devices, t 7 S, herein described, to bring therod j' of the forward eccentric into close proximity to the link-block(7', as shown in Fig. o', a :forward rotation is imparted to thecrank-shaft 7L of the engine, and when the link is adjusted to bring therod f of the backing eccentric into the same relation with thelink-block, as shown in Fig. S, a backward rotation is imparted to thecrank-shaft.

In carrying out my invention l have, illstead of providing duplicates ofthe abovedescribed devices as the means for operating the valve g of thesecond cylinder, provided the simpler devices which l will now describe.

7i represents an eccentric loosely ttcd on shaft 7L and adapted to turneasily thereon. (See Figs. l, 2, S, and et.) On said eccentric is litteda strap, 7i?, to which strap is secured an eccentric rod or 'blade, 7f3.Said rod or blade connected at its outer end to a rod, 71", which rodextends to and enters the steamchest c at the forward or outer end ofthe saine, Fig. 2, where it is connected with the valve g', as shown inFigs. (i, 7, and 8. Ec-

. centric 7L is provided with a project-ion, i, on

one side, adapted to engage with a projection or offset, fi', on acollar, i?, surrounding shaft 7L and secured thereto by set-screws or inany other suitable manner. The position of collar fi2 upon the shaft issuch that when the engine moving forward said collar will correspond tothe position of the forward eccentric, e, and the projection i of thecollar, coming into engagement with projection on eccentric 71 (thesaine being loose on shaft 7,) forces the eccentric 7L to conform to theposit-ion of the forward eccentric, c, and remain a forwardmotioneccentric as long as the engine continues to move in that direction. Theform of collar i2 and eccentric 7L and its projection f1', and theiroperative relation to each other, can be best understood by reference toFigs. 3, 4, and li.

The operation ol' the eccentric by collar 'i2 thus far described hasbeen forward, the valves of both cylinders opening and closing theirrespective ports exactly together, as will be seen by reference to Figs.-l and 7, where the engine is represented as in full gear forward-thatis, the piston at the forward end of the cylinders ce a and valves g ghave just commenced to open ports j j to admit steam to the pistons 7)Ui, the position of the link being such that the valve ,f/ gets fulltravel, which can be varied after starting by raising said link, andthereby imparting to valve g a shorter travel, as will be wellunderstood by all skilled in the use of link-motion engines.

Let it be supposed now that the engine is moving forward and it isdesired to reverse the direction of themovement. The position of thelink will. be changed to that shown in I Fig. S and the forwardeccentric, c, will become inoperative or out of gear, and the backingeccentric c, which has heretofore been inoperative while the engine hasbeen in full gear forward, is brought into operative positionv with thelink j by its rod or blade being brought into line with link-block f7and imparts motion to the same, and through it to the valve-rod (7 andvalve g, movements wh ich arc the .reverse of those produced by theadjustment shown in Figs. (i and 7, thus causing the valve g to admitsteam through thc port j and on the opposite side oli' the piston 71, asshown in cylinder (l, Fig. S. The reverse movement having been given tovalve y, the crank-shaft 7i', on which eccentric 72 and collar v172 arelocated, now rotates backwardly, as indicated bythe arrow in Fig. S, andol' course et'feentric 7l., bein g loose on said shaft, as stated, gwillremain motionlessin the position in which it left by collar i2before the change ol direction of motion of shat't 7l until the shaft 7lmakes a little less than a half-revolution, when. collar i2 engagesprojection 'i and carries eccentric 7L around, causing it to conform tothe position of liacking eccentric c and become also a backingeccentric, operating with the eccentric c', so that both valves g g areworked backwardly in unison.

In Fig. 5 I have shown a different 'l'orm ol' eccentric 71, which,instead ol' having a projection, fi, is provided with a cavity, 7c,which receives a feather secured to the shaft 7L in the saine relationto the eccentrics e e as is collar 2. Then the engine changes direction,the feather carried around with the shaft 7L and engages with theeccentric 71, as shown in Fig.

The travel or movement et' the valve y in connection with eccentric 7L is what is termed full travelV-that is, said valve being directlyconnected with the eccentric gets the full throw thereof. The beneiitderived from this arrangement is that the valve g has full travel, andthus gives full opening' to the ports jj, so that the admission of steamto and its escape from cylinder c is not varied, as it would be if valveg were controlled by a linkmotion, and thus baek-pressi'ire on the maincylinder is avoided to a great extent..

I prefer to make the cylinder a otI larger area than main cylinder a forseveral reasons, the principal one being that when the engine is beingreversed the valve g of the second cylinder remains motionless inposition. to prevent the escape oi' steam from said cylinder while theshaft is turnin sufiieiently to bring the collar lf2 into engagementwith projection "i, and back-pressure on the main piston will belessened by the enlarged area in cylinder d.

The link f2 is operated by the usual devices (shown in Figs. G and8)--viz., a saddle, 2, affixed to the link, having a pin, 3, to which.is attached a lifter, et, pivotally connected to an arm, 5, attached toa shaft, t5, and an arm,

7, also attached to said shaft, and a reach-rod,

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scribed, and thereby causing it to become either a forward or a backingeccentric, as said devices may be variously modified without departingvfrom the nature or spirit of my invention.

l claiml. ln a compound engine, the combination, with the main cylinder,its valve, and a linkmotion valve-gear therefor, of the second cyl- Yinder, a valve therefor, an eccentric, h, having a limited play on thecrank-shaft of the engine and adapted to conform either to the Aforwardor the backing eccentric of the main valve-gear, and a rod connectingsaid eccentric 72y and the valve of the second cylinder, as set forth.

2. The combination of the valve g, its valvegear, the eccentric h,having a projection, i, strap h2, and rod or blade 71,3, the collar i2,afxed to the crank-shaft and having the proj ection i" the valve g', andthe valve-r0d h4, 3o connected thereto and to the eccentric-rod h3,whereby the valve g is operated in unison with the main valve g, as setforth; y

3. In a compound engine, the combination, with the main cylinder, itsvalve, and link- 3 5 motion valve-gear, of the second cylinder, oflarger area than the main cylinder, the valve g of said second cylinder,the loose eccentric 7L, having a projection, t', the collar li2, afXedto the crank-shaft and havingl a projection, i', 4o and the' rods h3 h4,whereby the valve of the said second cylinder is operated in unison withthe valve of the main cylinder, as set forth. y

ln testimony whereof l have signed my name 4 5 to this specification, inthe presence of two subscribing witnesses, this 12th day of November, A.D. 1887.

lVlLLlAM E. PEARSON. lVitnesses:

C. F. BROWN, H. BROWN.

